Process for producing chlorogallium phthalocyanine crystal

ABSTRACT

In a process for producing a chlorogallium phthalocyanine crystal comprising mechanically dry-grinding chlorogallium phthalocyanine and subjected to crystal conversion, the weight ratio of chlorogallium phthalocyanine to the grinding media is set at a range of from 1/5 to 1/1000. The resulting chlorogallium phthalocyanine crystal excels in the dispersibility in a binding resin and the stability in the dispersion.

FIELD OF THE INVENTION

This invention relates to a process for producing a chlorogalliumphthalocyanine crystal by crystal conversion.

BACKGROUND OF THE INVENTION

Conventionally, various inorganic and organic photoconductive substanceshave been known as a photoconductive substance in an electrophotographicphotoreceptor. Since organic photoconductive substances, when being usedas an electrophotograph, have advantages of having excellenttransparency of the film, good film-forming ability and flexibility, andreduced cost, various substances have hitherto been suggested. In recentyears, there is an increasing requirement that a photosensitivewavelength region of the conventionally suggested organicphotoconductive substance extends to the wavelength of an infraredsemiconductor laser to use the substance as a photoreceptor for digitalrecording such as for a laser printer. From this viewpoint, squaraliliumcompounds described in JP-A-49-105536 (the term "JP-A" as used hereinmeans an unexamined published Japanese patent publication) andJP-A-58-21416, triphenylamine trisazo compounds described inJP-A-61-151659, phthalocyanine compounds described in JP-A-48-34189 andJP-A-57-148745 have been suggested as photoconductive materials for asemiconductor laser.

When organic photoconductive substances are used as a photoreceptor fora semiconductor laser, it is required first that they have aphotosensitive region extending to a long wavelength and then that thephotosensitive products formed have excellent sensitivity anddurability.

In order to satisfy these requirements, intense investigation anddevelopment have been tried and particularly, with regard tophthalocyanine compounds, various reports about their crystal forms andelectronically photographic characteristics have been made.

In general, it has been known that phthalocyanine compounds have severalcrystal forms depending on the difference of the treating processes andthe differences of the crystal forms have a great influence upon thephotoelectric transfer characteristics of the phthalocyanine compounds.As for the crystal forms of the phthalocyanine compounds, for example,concerning copper phthalocyanine, in addition to β form which is astable form, crystal forms such as α, ε, π, χ, ρ, γ, and δ forms havebeen known. These crystal forms have been known to be able to causemutual transition by mechanical deformation power, treatment withsulfuric acid, treatment with an organic solvent, thermal treatment, andother treatments (e.g., see U.S. Pat. Nos. 2,770,629, 3,160,635,3,708,292, and 3,357,989). As for non-metallic phthalocyanine, crystalforms such as α, β, γ, and χ have been known.

Moreover, with regard to chlorogallium phthalocyanine, the crystal formof chlorogallium phthalocyanine having a diffractive peak at a specificBragg angle has been described in Denshi Shasin Gakkai Shi, 26 (3), pp.240 (1987), but it has a crystal form different from that of theinvention, and there is no description of the application to anelectrophotograph in this literature. On the other hand, JP-A-59-44053and Shingaku Giho CPM 81-69, 39 (1981) report the application to anelectrophotograph, and JP-A-1-221459 discloses a chlorogalliumphthalocyanine having a diffractive peak at a specific Bragg's angle andan electrophotographic photoreceptor using the same.

However, the conventionally suggested phthalocyanines do not necessarilyhave a sufficient photosensitivity, and have problems in terms ofdispersibility in a binding resin and stability of the dispersion, andare disadvantageous in that they tend to cause image defects such asfogging and black spots. For these reasons, further improvement has beendesired.

The present invention has been done according to these requirements, andan object of the present invention is to solve the prior art's problems.

To be specific, the object of the present invention is to provide aprocess for producing a chlorogallium phthalocyanine crystal having ahigh sensitivity, excellent electrophotographic characteristics, andexcellent dispersibility in a binding resin and stability of dispersion.

SUMMARY OF THE INVENTION

As a result of our intense studies, it has been found that whenchlorogallium phthalocyanine obtained by synthesis is dry-ground(dry-pulverized) and subjected to crystal conversion, the weight ratioof chlorogallium phthalocyanine to the grinding media is set at a rangeof from 1/5 to 1/1000, thereby obtaining a chlorogallium phthalocyaninecrystal having a high sensitivity and excellent durability as aphotoconductive material, and that when this chlorogalliumphthalocyanine crystal is used as a charge generating material, theobject of the present invention can be achieved, thereby completing thepresent invention.

The process for producing a chlorogallium phthalocyanine crystal of thepresent invention is characterized in that when chlorogalliumphthalocyanine is mechanically dry-ground with a grinding media andsubjected to crystal conversion, the weight ratio of chlorogalliumphthalocyanine to the grinding media is set at a range of from 1/5 to1/1000.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a powder X-ray diffractive pattern of chlorogalliumphthalocyanine crystal obtained in Example 1; and

FIG. 2 shows a powder X-ray diffractive pattern of chlorogalliumphthalocyanine crystal obtained in Synthetic Example.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described below in detail.

The chlorogallium phthalocyanine which is used as a raw material in thepresent invention can be produced by any of the known syntheticprocesses such as a phthalonitrile process in which phthalonitrile ordiiminoisoindoline and a metal chloride are thermally melted or heatedin the presence of an organic solvent; a Wyler process in which phthalicanhydride, urea and a metal chloride are thermally melted or heated inthe presence of an organic solvent; a process in which cyanobenzamideand a metal salt are reacted at a high temperature; and a process inwhich dilithium phthalocyanine and a metal salt are reacted, and bythese synthetic processes, chlorogallium phthalocyanine (a) havingintense peaks at least at 11.0°, 13.5° and 27.1° of the Bragg anglerelative to Cu-Kα character X ray (2θ±0.2°) is produced. As the organicsolvents which are used in these synthetic processes, high boiling pointsolvents which are inert under the reaction such as α-chloronaphthalene,β-chloronaphthalene, methoxynaphthalene, diphenylethane, ethyleneglycol, dialkyl ethers, quinoline, sulfolane, dimethylsulfoxide,dichlorobenzene, and dichlorotoluene are desirable.

Chlorogallium phthalocyanine (a) obtained by any of these syntheticprocesses is mechanically dry-ground according to the present invention.Using a grinder for fine grinding by incorporating grinding media in theinterior of vessel such as of a vibration mill, a planetary ball mill, asand mill, a dino mill, a sueco mill, an attritor, and a ball mill,chlorogallium phthalocyanine (a) is dry-ground setting the weight ratioof chlorogallium phthalocyanine to the grinding media at a range of from1/5 to 1/1000. The period of pulverization may be from 1 to 300 hours,whereby the crystal conversion can be performed to obtain an intendedchlorogallium phthalocyanine crystal.

A vibration mill is the most effective grinder of the above-mentionedgrinders and can provide a high grinding efficiency. As the raw materialfor the grinding media, any known materials such as glass, alumina,zirconia, steel, stainless steel, carbon steel, chromium steel, siliconnitride, nylon, and polyurethane can be used. The shape of the grindingmedia which can be used is a known shape such as a globular, rod, orcylindrical form.

The weight ratio of chlorogallium phthalocyanine to the grinding mediais required to be from 1/5 to 1/1000, and is preferably from 1/10 to1/1000. If the weight ratio of chlorogallium phthalocyanine to thegrinding media is more than 1/5, the grinding efficiency is decreased,which needs a very long period for grinding and, thus, this is notpreferred in terms of production efficiency. Moreover, even when thegrinding period is extended, the fine grinding cannot be performed anylonger and, since particles having a small particle size cannot beobtained, a material having a high sensitivity cannot be obtained.Conversely, if the weight ratio is less than 1/1000, the recovery of thecrystal-converted chlorogallium phthalocyanine crystal is decreased and,at the same time, since the staining due to the wearing of the grindingmedia is increased, the image quality is adversely affected.

The thus crystal-converted chlorogallium phthalocyanine crystalpreferably has an average particle size of not more than 0.20 μm, andparticularly from 0.01 to 0.20 μm, by adjusting the grinding period. Ifthe average particle size exceeds 0.20 μm, the sensitivity of theresulting material is insufficient and the dispersibility is decreasedand, thus, image defects tend to be caused.

The chlorogallium phthalocyanine crystal which has beencrystal-converted by the process of the present invention has maindiffractive peaks at least at 7.5°, 16.7°, 25.6° and 28.4° of the Braggangle relative to Cu-Kα character X ray (2θ±0.2°), the half band widthat a peak of the Bragg angle of 7.5° is not less than 0.35, and the peakintensity ratio of the peak of the Bragg angle of 28.4° to the peak ofthe Bragg angle of 7.5° is from 0.4 to 0.7.

An embodiment where the chlorogallium phthalocyanine crystal obtained bythe process of the present invention is used as a photoconductivematerial in an electrophotographic photoreceptor will be describedbelow.

As the photoconductive materials in an electrophotographicphotoreceptor, those whose photosensitive layer has a single layerconstruction or whose photosensitive layer has a laminated constructionwhere a charge generating layer and a charge transport layer areseparately provided as their functions may be applied.

As the electroconductive substrate in the electrophotographicphotoreceptor, any substrate may be used as long as it has beenconventionally used. If required, the surface of the electroconductivesubstrate may be treated in various manners to the extent that there isno influence on the image quality. For example, an anodic oxidation ofthe surface, a surface coarsening treatment by liquid honing, a chemicaltreatment, or a coloring treatment can be carried out.

In the case of the laminated type photoreceptor, a photosensitive layerin which at least a charge generating layer and a charge transport layerare laminated may be provided on an electroconductive substrate, and asfor the order of the lamination, either layer may be near the substrate.

The charge generating layer may be composed of the chlorogalliumphthalocyanine crystal obtained by the process of the present inventionand a predetermined binding resin. In this case, no binding resin may beused. In addition to the chlorogallium phthalocyanine crystal, otherknown charge generating materials may be used together.

Any known binding resin can be used as the binding resin. Thecompounding weight ratio of the charge generating material to thebinding resin is preferably from 40:1 to 1:4, and more preferably from20:1 to 1:2. If the ratio of the charge generating material is too high,the stability of the coating liquid is decreased, and conversely, if itis to low, the sensitivity of the resulting material is lowered. Forthese reasons, the above-mentioned range is preferable.

As the solvents which can be used in the dispersion, organic solventssuch as methanol, ethanol, n-butanol, benzyl alcohol, methyl Cellosolve,ethyl Cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methylacetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran,methylene chloride, chloroform, benzene, toluene, xylene, chlorobenzene,dimethylformamide, and dimethyl acetamide, and the mixed solventsthereof can be used. As means for dispersing, a method using a sandmill, a colloid mill, an attritor, a ball mill, a dino mill, a co-ballmill, and a roll mill can be used. As the coating process, methods suchas a blade coating, a wire bar coating, a spray coating, a dip coating,a bead coating, and a curtain coating, can be utilized.

The film thickness of the charge generating layer is preferably from0.01 to 5 μm, and more preferably from about 0.03 to 2 μm.

The charge transport layer may be composed of a charge transportmaterial and a film-forming resin, and any known material can be used.Examples of the film-forming resin include polycarbonates,polyallylates, polystyrenes, polyesters, styrene-acrylonitrilecopolymers, polysulfones, polymethacrylates, styrene-methacrylatecopolymers, polyolefins, etc. Of these, polycarbonates are suitable interms of durability.

The compounding weight ratio of the charge transport material to thefilm-forming resin is preferably from 5:1 to 1:5, and more preferablyfrom 3:1 to 1:3. If the ratio of the charge material is too high, themechanical strength of the charge transport layer is decreased and,conversely, if it is too low, the sensitivity is lowered. For thesereasons, the above-mentioned range is preferable. If the chargetransport material has a film-forming ability, the film forming resincan be omitted.

The charge transport material layer is formed by dissolving the chargetransport material and the film-forming resin in an appropriate solvent,followed by application, and it is preferable to form the layer in sucha manner that the film thickness preferably becomes in the range of from5 to 50 μm, and more preferably from 10 to 40 μm.

As the methods for applying the photosensitive layer, any of the methodsdescribed in the charge generating layer can be used.

When the photosensitive layer has a single layer construction, thephotosensitive layer is composed of a photoconductive layer having thechlorogallium phthalocyanine crystal and the charge transport materialdissolved in the film forming resin. As the charge transport material,any known material can be used, and as the film forming resin, amaterial similar to those described above is used. The photosensitivelayer is formed by any of the above-mentioned methods. It is preferableto set the compounding weight ratio of the charge transport material tothe film forming resin at the range from 1:20 to 5:1, and thecompounding weight ratio of the chlorogallium phthalocyanine crystal tothe charge transport material at the range from 1:10 to 10:1.

If necessary, an undercoat layer may be provided between thephotosensitive material and the substrate. The undercoat layer iseffective for preventing the injection of unnecessary electric chargefrom the substrate, and has a function of enhancing charging properties.Also, it has a function of enhancing the adhesion between thephotosensitive layer and the substrate.

In addition, in order to improve printing resistance, a protective layer(i.e., overcoat layer) may be provided on the photosensitive layer.

The resulting electrophotographic photoreceptors can be effectively usedin an electrophotographic copying machine, and it is also applicable toa laser beam printer, an LED printer, a CRT printer, a microfilm reader,a normal paper facsimile, and an electrophotographic printing system.

The chlorogallium phthalocyanine crystal obtained by the process of thepresent invention can provide an electrophotographic photoreceptorexhibiting a high sensitivity, excellent electrophotographiccharacteristics, and excellent dispersibility, and having excellentimage quality without fogging and black spots by incorporating it in aphotosensitive layer as a charge generating material. Furthermore, sincethe process for producing a chlorogallium phthalocyanine crystal of thepresent invention can be carried out in a simple stage and does notrequire complicated installation, a chlorogallium phthalocyanine crystalhaving good characteristics can be stably obtained with less impact interms of cost.

The present invention will now be described in greater detail byreferring to Examples. In Examples, the "part" is based on weight.

SYNTHETIC EXAMPLE (SYNTHESIS OF CHLOROGALLIUM PHTHALOCYANINE)

In 230 parts of quinoline were put 30 parts of 1.3-diiminoisoindolineand 9.1 parts of gallium trichloride. The mixture was reacted at 180° C.for 4 hours. Thereafter, the product was filtered off, washed withN,N-dimethylformamide and with methanol, and the wet cake was then driedto obtain 28 parts of chlorogallium phthalocyanine. The powder X raydiffraction of the resulting chlorogallium phthalocyanine is shown inFIG. 2. The elemental analysis gave the following data:

    ______________________________________                                                    C    H          N      Cl                                         ______________________________________                                        Calculated (%)                                                                              62.22  2.61       18.14                                                                              5.74                                     Found (%)     62.11  2.63       18.00                                                                              5.70                                     ______________________________________                                    

When the average particle size of the chlorogallium phthalocyaninecrystal was determined with Laser Scattering Particle Size DistributionAnalyzer (LA 700, produced by Horiba Seisakusho), it was found to be45.0 μm.

EXAMPLE 1

In an alumina-made pot were put 5 parts of the chlorogalliumphthalocyanine crystal obtained in Synthetic Example together with 250parts of an alumina-made ball having a diameter of 15 mm (weight ratioof chlorogallium phthalocyanine crystal to the alumina-made ball: 1/50).The pot was provided on a vibration mill (MB-1, produced by ChuoKakoki), and the crystal was ground over a period of 100 hours. FIG. 1shows the powder X ray diffraction pattern of the resultingchlorogallium phthalocyanine crystal.

From the results of the powder X ray diffraction, it was found that thehalf band width at the peak of a Bragg angle of 7.5° was 0.62, and thepeak intensity ratio of the peak of the Bragg angle of 28.4° to the peakof the Bragg angle of 7.5° was 0.46. When the average particle size ofthe chlorogallium phthalocyanine crystal at that time was determined, itwas found to be 0.14 μm.

EXAMPLE 2

In a glass-made ball mill were put 5 parts of the chlorogalliumphthalocyanine crystal obtained in Synthetic Example together with 50parts of an alumina-made ball having a diameter of 15 mm (weight ratioof chlorogallium phthalocyanine crystal to the alumina-made ball: 1/10).The pot was provided on a vibration mill (MB-1, produced by ChuoKakoki), and the crystal was ground over a period of 100 hours. Thepowder X ray diffraction pattern of the resulting chlorogalliumphthalocyanine crystal was similar to that of Example 1. From theresults of the measurement, it was found that the half band width at thepeak of a Bragg angle of 7.5° was 0.41, and the peak intensity ratio ofthe peak of the Bragg angle of 28.4° to the peak of the Bragg angle of7.5° was 0.43. When the average particle size of the chlorogalliumphthalocyanine crystal at that time was determined, it was found to be0.20 μm.

EXAMPLE 3

In an alumina-made pot were put 5 parts of the chlorogalliumphthalocyanine crystal obtained in Synthetic Example together with 350parts of glass beads having a diameter of 15 mm, set on a ball mill'strestle, and ground over a period of 120 hours (weight ratio ofchlorogallium phthalocyanine crystal to the glass beads: 1/70). Thepowder X ray diffraction of the resulting chlorogallium phthalocyaninecrystal was similar to that of Example 1. From the results of themeasurement, it was found that the half band width at the peak of aBragg angle of 7.5° was 0.56, and the peak intensity ratio of the peakof the Bragg angle of 28.4° to the peak of the Bragg angle of 7.5° was0.49. When the average particle size of the chlorogallium phthalocyaninecrystal at that time was determined, it was found to be 0.17 μm.

EXAMPLE 4

In an aluminum-made pot were put 10 parts of the chlorogalliumphthalocyanine crystal obtained in Synthetic Example together with 250parts of an alumina-made ball having a diameter of 15 mm (weight ratioof chlorogallium phthalocyanine crystal to the alumina-made ball: 1/25).The pot was provided on a vibration mill (MB-1, produced by ChuoKakoki), and the crystal was ground over a period of 100 hours. Thepowder X ray diffraction pattern of the resulting chlorogalliumphthalocyanine crystal was substantially similar to that of Example 1.From the results of the measurement, it was found that the half bandwidth at the peak of a Bragg angle of 7.5° was 0.62, and the peakintensity ratio of the peak of the Bragg angle of 28.4° to the peak ofthe Bragg angle of 7.5° was 0.46. When the average particle size of thechlorogallium phthalocyanine crystal at that time was determined, it wasfound to be 0.14 μm.

EXAMPLE 5

In an alumina-made pot were put 5 parts of chlorogallium phthalocyaninecrystal obtained in Synthetic Example together with 25 parts of analumina-made ball having a diameter of 15 mm (weight ratio ofchlorogallium phthalocyanine crystal to the alumina-made ball: 1/5). Thepot was provided on a vibration mill (MB-1, produced by Chuo Kakoki),and the crystal was ground over a period of 100 hours. The powder X raydiffraction pattern of the resulting chlorogallium phthalocyaninecrystal was substantially similar to that of Example 1. From the resultsof the measurement, it was found that the half band width at the peak ofa Bragg angle of 7.5° was 0.41, and the peak intensity ratio of the peakof the Bragg angle of 28.4° to the peak of the Bragg angle of 7.5° was0.43. When the average particle size of the chlorogallium phthalocyaninecrystal at that time was determined, it was found to be 0.20 μm.

EXAMPLE 6

In a glass-made ball mill were put 5 parts of chlorogalliumphthalocyanine crystal obtained in Synthetic Example together with 500parts of glass beads having a diameter of 15 mm, set on a ball mill'strestle, and ground over a period of 120 hours (weight ratio ofchlorogallium phthalocyanine crystal to the glass beads: 1/100). Thepowder X ray diffraction pattern of the resulting chlorogalliumphthalocyanine crystal was similar to that of Example 1. From theresults of the measurement, it was found that the half band width at thepeak of a Bragg angle of 7.5° was 0.56, and the peak intensity ratio ofthe peak of the Bragg angle of 28.4° to the peak of the Bragg angle of7.5° was 0.49. When the average particle size of the chlorogalliumphthalocyanine crystal at that time was determined, it was found to be0.17 μm.

COMPARATIVE EXAMPLE 1

In an alumina-made pot were put 5 parts of chlorogallium phthalocyaninecrystal obtained in Synthetic Example together with 15 parts of analumina-made ball having a diameter of 15 mm (weight ratio ofchlorogallium phthalocyanine crystal to the alumina-made ball: 1/3). Thepot was provided on a vibration mill, and the crystal was ground over aperiod of 100 hours. At that time, a large amount of cohesion of thechlorogallium phthalocyanine crystal was observed in the pot. From theresults of the powder X ray diffraction pattern of the resultingchlorogallium phthalocyanine crystal, it was found that the half bandwidth at the peak of a Bragg angle of 7.5° was 0.26, and the peakintensity ratio of the peak of the Bragg angle of 28.4° to the peak ofthe Bragg angle of 7.5° was 0.20. When the average particle size of thechlorogallium phthalocyanine crystal at that time was determined, it wasfound to be 0.29 μm.

COMPARATIVE EXAMPLE 2

In a glass-made ball mill were put 5 parts of chlorogalliumphthalocyanine crystal obtained in Synthetic Example together with 20parts of glass beads having a diameter of 15 mm, set on a ball mill'strestle, and ground over a period of 120 hours (weight ratio ofchlorogallium phthalocyanine crystal to the glass beads: 1/4). At thattime, a large amount of cohesion of the chlorogallium phthalocyaninecrystal was observed in the mill. From the results of the powder X raydiffraction pattern of the resulting chlorogallium phthalocyaninecrystal, it was found that the half band width at the peak of a Braggangle of 7.5° was 0.31, and the peak intensity ratio of the peak of theBragg angle of 28.4° to the peak of the Bragg angle of 7.5° was 0.32.When the average particle size of the chlorogallium phthalocyaninecrystal at that time was determined, it was found to be 0.36 μm.

EXAMPLE 7

As described in JP-A-2-87154, a wet honing treatment of aluminum pipewas carried out as follows as described in JP-A-2-87154. Amirror-surface aluminum pipe having a diameter of 40 mm and a length of319 mm was prepared. Using a liquid honing apparatus, 10 kg of abrasive(Green Desick GC #400, produced by Showa Denko) was suspended in 40 l ofwater, and the suspension was transported to a gun at a flow rate of 6l/min., and a wet-honing was carried out at a blowing rate of 60mm/min., and at an air pressure of 0.85 kgf/cm², while moving thealuminum pipe to the axis direction with rotating it at 120 rpm. Thecenter line coarseness, R₃, at that time was 0.16 μm. Subsequently, 8parts of a polyvinyl butyral resin (S-lec BM-S, produced by SekisuiChemicals) was added to 152 parts of n-butyl alcohol, and dissolved withstirring to prepare a 5% by weight polyvinyl butyral solution.Subsequently, a solution prepared by mixing 100 parts of a 50% solutionof tributoxyzirconium acetylacetonate in toluene (ZC 540, MatsushitaTrading), 10 parts of γ-aminopropyl-triethoxysilane (A 1100, produced byNippon Unicar), 130 parts of n-butyl alcohol was added to theabove-prepared polyvinyl butyral solution, stirred with a stirrer tothereby prepare a coating liquid for the formation of a layer. Thiscoating liquid was impregnated and coated on the aluminum pipe,thermally dried at 150° C. for 10 minutes to form a 1.0 μm thickundercoat layer.

On the other hand, 3 parts of the chlorogallium phthalocyanine crystalprepared in Example 1 was added to a solution of 3 part of polyvinylbutyral resin (S-lec BM-S, produced by Sekisui Chemicals) dissolved in100 parts of a mixed solution of xylene/n-butyl acetate (mixing ratio:1/5), dispersed by a sand mill for 6 hours, and diluted with theabove-mentioned xylene/n-butyl acetate mixed solution to prepare acoating solution for the formation of a charge generating layer having asolid concentration of 3.0% by weight. The resulting coating solutionwas subjected to ring coating on the above-mentioned undercoat layer,thermally dried at 100° C. for 10 minutes to form a 0.20 μm thick chargegenerating layer.

On the formed charge generating layer was formed a charge transportlayer. To be specific, 4 parts ofN,N'-bis-(p-tollyl)-N,N'-(p-ethylphenyl)-3,3'-dimethylbenzidine as acharge transport material and 6 parts of polycarbonate Z resin weredissolved in 40 parts of monochlorobenzene, and the resulting solutionwas coated on the charge generating layer by an impregnating applicationapparatus, followed by thermally drying at 115° C. for 60 minutes toprepare a 20 μm thick charge transport layer. This gave anelectrophotographic photoreceptor.

EXAMPLE 8

An electrophotographic photoreceptor was produced as in Example 7 exceptfor using as a charge generating material the chlorogalliumphthalocyanine crystal prepared in Example 2 instead of that in Example1.

EXAMPLE 9

An electrophotographic photoreceptor was produced as in Example 7 exceptfor using as a charge generating material the chlorogalliumphthalocyanine crystal prepared in Example 3 instead of that in Example1.

EXAMPLE 10

An electrophotographic photoreceptor was produced as in Example 7 exceptfor using as a charge generating material the chlorogalliumphthalocyanine crystal prepared in Example 4 instead of that in Example1.

EXAMPLE 11

An electrophotographic photoreceptor was produced as in Example 7 exceptfor using as a charge generating material the chlorogalliumphthalocyanine crystal prepared in Example 5 instead of that in Example1.

EXAMPLE 12

An electrophotographic photoreceptor was produced as in Example 7 exceptfor using as a charge generating material the chlorogalliumphthalocyanine crystal prepared in Example 6 instead of that in Example1.

COMPARATIVE EXAMPLE 3

An electrophotographic photoreceptor was produced as in Example 7 exceptfor using as a charge generating material the chlorogalliumphthalocyanine crystal prepared in Synthetic Example instead of that inExample 1.

COMPARATIVE EXAMPLE 4

An electrophotographic photoreceptor was produced as in Example 7 exceptfor using as a charge generating material the chlorogalliumphthalocyanine crystal prepared in Comparative Example 1 instead of thatin Example 1.

COMPARATIVE EXAMPLE 5

An electrophotographic photoreceptor was produced as in Example 7 exceptfor using as a charge generating material the chlorogalliumphthalocyanine crystal prepared in Comparative Example 2 instead of thatin Example 1.

For these electrophotographic photoreceptors, using a laser printerremodeled scanner (XP-11 modified machine, produced by Fuji Xerox), theelectric potentials of several parts were measured by a process in which(A) they are charged with a scorotoron charger having a grid applyingelectric voltage of -600 V at 20° C. and at 50% RH, (B) irradiated witha light of 7.0 ergs/cm² to carry out discharge using a semiconductorlaser after 1 minute, and (C) irradiated with a red LED ray to removethe electric charge after 3 minutes. The higher the electric potential(V_(H)) in (A) is, the higher the receiving electric potential of aphotosensitive material is, in which case the photosensitive materialcould take a high contrast. The lower the electric potential (V_(L)) in(B) is, the higher the sensitivity is, and the lower the electricpotential (V_(RP)) in (C) is, the smaller the residual electricpotential is, evaluating that the photoreceptor has less image memoryand fogging. Moreover, the electric potentials of several portions weremeasured after 5000 times repeated charging and exposure. Furthermore,for these electrophotographic photoreceptors, the evaluation of theimage quality was carried out at 30° C. and at 85% RH using a laserprinter (XP-11, produced by Fuji Xerox). These results are shown inTable 1.

                                      TABLE 1                                     __________________________________________________________________________                                Initial     5000 times repeated                                 Average                                                                            7.5°                                                                       28.4°/                                                                      potential (V)                                                                             potential (V)                                Charge particle                                                                           half                                                                              7.5° peak                                                                   Poten-                                                                            Poten-                                                                            Poten-                                                                            Poten-                                                                            Poten-                                                                            Poten-                        Photo- generating                                                                           size band                                                                              intensity                                                                          tial A                                                                            tial B                                                                            tial C                                                                            tial A                                                                            tial B                                                                            tial C                                                                            Image                     receptor                                                                             material                                                                             (μm)                                                                            width                                                                             ratio                                                                              V.sub.H                                                                           V.sub.L                                                                           V.sub.RP                                                                          V.sub.H                                                                           V.sub.L                                                                           V.sub.RP                                                                          quality                   __________________________________________________________________________    Example 7                                                                            Example 1                                                                            0.14 0.62                                                                              0.46 -585                                                                               -70                                                                              -30 -585                                                                               -65                                                                              -30 Good                      Example 8                                                                            Example 2                                                                            0.20 0.41                                                                              0.43 -590                                                                              -110                                                                              -70 -585                                                                              -100                                                                              -65 Good                      Example 9                                                                            Example 3                                                                            0.17 0.56                                                                              0.49 -590                                                                               -90                                                                              -40 -585                                                                               -85                                                                              -35 Good                      Example 10                                                                           Example 4                                                                            0.14 0.62                                                                              0.46 -590                                                                               -75                                                                              -30 -590                                                                               -70                                                                              -30 Good                      Example 11                                                                           Example 5                                                                            0.20 0.41                                                                              0.43 -590                                                                              -105                                                                              -70 -590                                                                              -100                                                                              -65 Good                      Example 12                                                                           Example 6                                                                            0.17 0.56                                                                              0.49 -595                                                                               -90                                                                              -40 -590                                                                               -90                                                                              -35 Good                      Comparative                                                                          Synthetic                                                                            45.0 --  --   -575                                                                              -200                                                                              -150                                                                              -570                                                                              -190                                                                              -145                                                                              Black spots               Example 3                                                                            Example                                      were                                                                          generated                 Comparative                                                                          Comparative                                                                          0.29 0.26                                                                              0.20 -585                                                                              -145                                                                              -120                                                                              -570                                                                              -130                                                                              -110                                                                              Black spots               Example 4                                                                            Example 1                                    were                                                                          generated                 Comparative                                                                          Comparative                                                                          0.36 0.31                                                                              0.32 -590                                                                              -165                                                                              -130                                                                              -575                                                                              -150                                                                              -120                                                                              Black spots               Example 5                                                                            Example 2                                    were                                                                          generated                 __________________________________________________________________________

What is claimed is:
 1. A process for producing a chlorogalliumphthalocyanine crystal, which comprises mechanically dry-grindingchlorogallium phthalocyanine with a grinding media to produce acrystal-converted chlorogallium phthalocyanine crystal, wherein theweight ratio of said chlorogallium phthalocyanine to said grinding mediais from 1/5 to 1/1000.
 2. The process as claimed in claim 1, whereinsaid crystal-converted chlorogallium phthalocyanine crystal has intensediffraction peaks at Bragg angles (2θ±0.2°) of 7.5°, 16.7°, 25.6° and28.4°, a half width at the peak of the Bragg angle of 7.5° is not lessthan 0.35, and a peak intensity ratio of the peak of the Bragg angle of28.4° to that of 7.5° is from 0.4 to 0.7.
 3. The process as claimed inclaim 1, wherein said chlorogallium phthalocyanine has intensediffraction peaks at Bragg angles (2θ±0.2°) of 11.0°, 13.5° and 27.1°.4. The process as claimed in claim 1, wherein said crystal-convertedchlorogallium phthalocyanine crystal has an average particle size of notmore than 0.20 μm.
 5. The process as claimed in claim 2, wherein saidcrystal-converted chlorogallium phthalocyanine crystal has an averageparticle size of not more than 0.20 μm.